Method for cooking foodstuffs

ABSTRACT

A method for cooking foodstuffs by immersing them in a heated liquid cooking medium contained in a pressure vessel, closing the vessel and relieving the pressure therein when it reaches a predetermined high limit. The pressure is then relieved to a low limit. The cycle is repeated until the foodstuffs are cooked. The cooking medium is then discharged from the vessel under the urging of the pressure of the steam remaining in the vessel. Upon complete discharge of the cooking medium, the vessel is completely vented of residual steam. The discharged cooking medium, if desired, is filtered of all solid residue and is then ready for reuse.

Mw 7, 1974 N. w. THoMPsoN 3,809,777

METHOD FOR COOKING FOODSTUFFS l Filed Sept, 30, 1971 4 Sheets-Sheet l May 7, |974 N. w. THOMPSON 3,809,777

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20T Q 15| VE H4 qu v INVENoR Neal W. Thompson ay 7, i974 N. w. THOMPSON 3,309,777

METHOD FOR COOKING FOODSTUFFS Filed Sept. 50, 1971 4 Sheets-Sheet 5 INVENTOR Neal W. Thompson 7 W74 N. w. THOMPSON 3,809,777

MFTHOD FOR COOKING FOODSTUFFS Filed Sept. 30, 1971 4 Sheets-Sheet 4 INVENoR Neal W. Thompson United States Patent O 3,809,777 METHOD FOR COKING FOODSTUFFS Neal W. Thompson, 6097 Steubenville Pike, McKees Rocks, Pa. 15136 Continuaton-n-part of abandoned application Ser. No.

665,478, Sept. 5, 1967, and a division of application f Ser. No. 747,760, July 1, 1968. This application Sept. 30, 1971, Ser. No. 185,183

Int. Cl. A22c 18/00 U.S. Cl. l 426--438 12 Claims ABSTRACT OF THE DISCLOSURE A method for cooking foodstuffs by immersing them in a heated liquid cooking medium cont-ained in a pressure vessel, closing the vessel and relieving the pressure therein when it reaches a predetermined high limit. The pressure SPECIFICATION This application is a continuation-in-part of U.S. patent application Ser.` No. 665,478, vtiled Sept. 5, 1967, now abandoned and a divisional application of my pending U.S. patent application Ser. No. 747,760, tiled July 1, 1968, now Pat. No. 3,613,550 issued Oct. 19, 1971.

A well known method of preparing certain foodstuffs, such as chicken, sea food, various kinds of meats, and the like is to immerse these foodstuffs in hot shortening or fat and cook the foodstuffs until done. This type of food preparation is commonly called deep frying. Establishments handling large quantities of food often resort to such deep frying under pressure. Pressure type deep frying permits the food `to be prepared in relatively short time as compared to open type deep frying. One problem is common to both the open type and pressure type of deep frying systems, namely, the shortening or fat h-as a limited useful life and must be completely replaced at regular intervals. The reason for this limited life is that after a certain period of use the fat breaks down, characterized by foaming, a dark amber color, off davor, smoking, and formation of gums and residues. This break down of the fat is due to -the chemical formation therein of a high degree of free fatty acids. These adverse and destructive free fatty acids have been attributed to the breakdown of the chemical bond between the glycerine and fatty acids which make up the fat. This breakdown is due mainly to hydrolysis, the presence of contaminating impurities in the fat, and sustained use of impurity contaminated fat at high temperatures. The impurities often found in the fat are derived in large part from the food being prepared. For example, chicken during deep frying will release, among other things, a product commonly called glue. Residual bloo'd remaining in the chicken may also be released. In addition to the glue and blood, our, bread particles, salt, spices and the like forming parts of the covering or breading applied to the chicken will also enter into the fat as part of the total impurities. Straining and ltering of the fat helps to add to the effective life of the fat. However, most of the filtering systems, aside from being elaborate, expensive, and awkward cannot effectively prevent breakdown of the fat since the destructive free fatty acids are formed, while the fat is being used at high temperatures to fry food and remain in solution with the fat and cannot be filtered out. Oftentimes the ICC fat is not permitted to be used until it completely breaks down Ibut is replaced on a regular basis, usually on the basis of change in color. The reason for this is that the contaminated fat, if not replaced, will give the food an undesirable off flavor and unattractive appearance, and this is attributed Ito the high degree of free fatty acids in the fat, and the adhesion of carbon particles already formed, as well as the other suspended impurities to the foods. In addition to causing breakdown of the fat, the impurities transfer an odor or off flavor to the fat, such odor or off flavor being characteristic of the particular food being prepared. For example, the fat used for preparing chicken would smell like the chicken. Odorous fat cannot be used in preparing other foods due to the danger of the odor of one food being transferred to the other food (viz. fishy smelling chicken).

The rate of formation of free fatty acids due to the presence of impurities and moisture in the fat is accelerated when the fat is used at sustained high temperatures. Accordingly, the temperature of the fat is kept relatively low during cooking (e.g., 325 to 350 F.). The cooking time for the food product is necessarily lengthened as compared with fat used at higher temperatures.

As mentioned earlier, hydrolysis is a cause of fat breakdown and is due to excess water in the fat. An excessive amount of Water in the fat also results in the rapid generation of steam as the fat is heated to high temperatures. This rapid generation of steam causes violent sputtering which is dangerous to anyone who might be near 4an open fryer. The sputtering caused by the generated steam also carries some of the fat away to be thus wasted. In order to avoid sputtering by generated steam when deep frying refrigerated foods, a common practice has been to preheat or blanch the refrigerated foods to drive off some of its moisture. Aside from necessitating an additional procedure in preparing these refrigerated foods, this preheating is unsanitary and can result in food contamination. Some states have recognized this unsanitary danger of pre-heating refrigerated foods by prohibiting restaurants and the like from pre-heating refrigerated foods prior to cooking.

Water also plays an important favorable role in deep frying operations and particularly in pressure deep frying. The steam generated from the moisture in the foods being fried circulates through the fat and contacts the food to restore the lost moisture thereby resulting in a tender, moist and tasty food product. An additional problem arises here, however, and especially in pressure frying in that the steam, if not properly controlled, can cause the food to become over-cooked. In the case of chicken, for example, the meat can fall away from the bones if overcooked. If the steam is generated too rapidly in open deep frying, and thereby not permitted to circulate about the food, the food will tend to char since it will be getting too much heat too fast. Therefore, the temperature of the fat during cooking cannot be raised too high.

, One other problem common to both open type and pressure type deep frying is that the food product absorbs and retains a certain amount of fat which detracts from the taste of the food as well as being another source of fat waste. The amount of fat absorbed by the food product increases as the length of cooking time increases. The cooking times currently used are unnecessarily long because of the necessity of using low fat temperatures, as indicated previously. Conscientious restaurants oftentimes use a degreaser or defatter for removing the residual fats in the food products. Degreasing adds a time consuming step to the food processing procedure, with the degreasers or defatters having the additional disadvantages of being expensive and bulky.

Pressure type deep fryers are always explosion problems, especially if operated at very high pressures such as above 35 p.s.i.g. Furthermore, the food product resulting from the use ofthe pressure fryers extant are not Vsatisfactory, due mainly to the water and impurities mentioned earlier. The dissatisfaction with high pressure fryers is demonstrated by the scarcity of use ofthese known pressure fryers.

The pressure deep fry systems commonly used are also limited in the amount of food product which can be prepared in individual vessels. One process extensively used being served. Needless to say, the just described process" is inefficient, wasteful of valuable cooking fat, dangerous vto operators who have to open the containers and carry them to the strainer vats, very expensive to operateand other deiiciencies too numerous to mention.

Pressure cooking is also used for preparing other food products, such as stewed chicken, pot roasted beef, vegetables, and dough products, for example, with water being used as the cooking medium. The water is either discarded or used as gravy stock, in the case of meats, after the cooking of the products is completed. In the case of pressure cookers used to date, anycontaminating foreign matter on the products tends to recirculate about the cooking vessel and either remain on the product, in the water, or on the walls of the vessel. In other words, there is no way for foreign matter to escape from the cooking vessel during cooking.

I have overcome the problems indigenous to the commonly used deep frying cookers and to pressurecookers using a liquid cooking medium by providing'a newmethod for cooking comprising, preferably, the steps of: immersing foodstuffs in `a scalable pressure vessel containing a liquid cooking medium at a temperature sufficient to" cook the foodstuffs; closing the vessel to render it pressure-tight; heating the cooking medium until'the pressure in the vesfish such as tuna and Swordfish have been reduced by being cooked following the steps of my method. Finally, my method can be used with small or large quantities of foodstuffs and provides a thoroughly and uniformly cooked product throughout the entire mass of product in the cooking vessel.

Other details, objects and advantages of the invention will become apparent as the following description of a present preferred method of practicing my invention.

In the accompanying drawings, I have illustrated a .present preferred method of the same in which:.

FIG. l is a side elevational view partly in section and partly diagrammatical of one pressure cooking system for practicing the present invention;

FIG. 2 is a schematic representation of a typical control system for use with the present invention;

FIGS. 3-7 show schematic representations of foodstuffs being prepared in accordance with the present invention; and

FIG. 8 is a schematic representation of another pressure cooking system for practicing the present invention.

Referring now to the drawings wherein like reference numeralsv refer to like parts throughout the views, 10 generally represents one embodiment of a pressure type deep fry system for practicing the present invention. For purposes of clarity of description the deep fry system 10 will be considered as a system for preparing chicken sections by using the familiar, non-aqueous vegetablev shortening or fat as the cooking medium. The shortening will hereinafter be called fat. As illustrated, the deep fry systern 10 includes a generally cylindrical high pressure, large capacity (viz gallons, for example) cooking vessel 12 for suitably containing hot fat 13. Vessel 12 is suitably internally adapted for reciving and supporting mesh trays 14 (tive shown) containing pieces of chicken and suitably tandomly stacked on a support rod 15. Vessel 12 is Vadapted to be closed in a pressure tight condition by cover 16 suitably pivotably mounted on vessel 12. Cover 16 carries a gasket 17 or the like, which when pressed down against the upper edge of the vessel 12 provides a seal'capable of withstanding relatively high pressures. The cover 16is securely fixed in place with vessel12by a v.plurality of lever-type toggle clamps 18, one illustrated,

sel increases to a first value; relieving the pressure in the" vessel from the rst value to a second Value to release a portion of steam; continuing the relieving and the heating until the foodstuffs are cooked; discharging the cooking medium from the vessel; and venting the Vessel of all of the steam therein upon completion of the Idischarging of pivotably supported and circumferentially spaced about .an upper portion of vessel 12, which clamps 18 engage .yoke-like lugs 19 fixed on cover 16.

Vessel 12 communicates through suitable plumbing ,withr` a pair of juxtaposed storage containers 21 and 23 formed preferably from stainless steel sheet and suitably heat insulated. Container 21 is used `.for storingY clean very little loss of the shortening due to sputtering and/or` adherence tothe food and, more importantly, the shortening discharged from the vessel is free of la large portion-of deleterious free fatty acids which would otherwise react to break it down and to give the'shortening the odor of the food being prepared. The shortening can thus beremersion heater 27 suitably connected to a source of electricity is positioned in the container 21 for heating the fat therein. Plumbing 28 extends between a lower portion of container 21 and a double acting pump 29 driven by a re- V versible electrical motor 30 suitably connected to a source 'i of electrical power. A solenoid operated valve 26 is dis- `posed in plumbing 28 between container 21 and pump 29. Pump 29 communicates through its output side with vessel 12 through plumbing 32 which includes pipes 33 and When either shortening or water is used as the cooking-y medium a large portion of lightweight foreignmatter which may have been on the surface of the food or in the cooking medium or in the food itself is removed during can, if desired, be either used as stock for gravy, in the case of cooking meats in water, or discarded. Additionally, my method is more than reasonably safe sinceit canI be operated at a relatively low-pressure as compared to'the` pressure cooking systems known today. Also, certain test results have shown that the mercury contents in various 34 coupled by two ends of T connection 35. The remainder of plumbing -32 includes a length of pipe 37 suitably connected with vessel 12 at the bottom thereof, which pipe 37 extends to one end of four-way coupling 38. Pipe 34 is suitably connected by a length of pipe 39 to a solenoid operated valve 40 which in turn is suitably connected to anend ofA coupling 38 by pipe 41. The valve 40 is arranged to .permit ow from the pump 29 to and from vesselr 12 as will be described hereinafter. Vessel 12 communicates with vcontainer 23 through pipe 37, four-way coupling 38, pipe 43 connected with coupling 38, and then through solenoid operated valve 45 connected at one end to a pipe 46 and at the other end to a length of pipe 47 which in turn is suitably connected with one end of a T connector 48 and then through a pipe 50 and 51 to a lower end portion of container 23. Container 23 receives the fat from vessel 12 after the cooking cycle is completed, as will be fully described hereinafter. The fat will be put into container 21 so that it may be reused for another cooking cycle. The fat will, however, be ltered of residual particulate matter before being put into container 21. A mesh strainer 53 preferably made of stainless steel is suitably xed in the container 23 through a lower portion thereof. A length of pipe 52 extends from strainer 53 to a solenoid operated value 57 arranged to open when filling container 21 with the fat from container 23. Another length of pipe 59 extends from Valve 57 to T connector 35. Solenoid valve 57 is arranged to only permit ow from container 23 to container 21.

A length of pipe 61 extends from T connector 48 to a solenoid operated valve 62 which in turn is suitably connected by pipe 63 to a T connector 64 disposed in plumbing 28.

A steam vent line 66 extends outwardly from an upper portion of vessel 12 and extends to a T connection 55 which in turn is connected by a short section of pipe 69 to a solenoid operated valve 68 which in turn is connected by a section of pipe 94 to one end of a four-way coupling 70. A length of pipe 71 is connected to another end of four-way coupling 70, which pipe 71 is open to a sewer line, not shown. The solenoid operated valve 68 is set to open by means, to be described later, when the pressure in vessel 12 reaches about 15 p.s.i.g. and to close again when the pressure in vessel 12 is relieved from 15 p.s.i.g. to about p.s.i.g. A length of pipe 85 is suitably connected between coupling 70 and solenoid operated valve 87 which in turn is connected to a length of pipe 88 which is connected to one end of four-way coupling 38.

A safety relief valve 91 is connected at one end thereof by pipe 92 to T connector 55 and at the other end thereof to a plumbing 93 which is suitably connected to four-way coupling 70.

The fat in vessel 12 is heated before the cooking cycle begins and during the cooking cycle while the pressure in the vessel is building up. The heating of the fat in vessel 12 is provided by gas burners 75 suitably connected to a source of gas through plumbing 76. The flow of ygas to the burners 7S is regulated by regulating valve 77 suitably connected with plumbing 76.

A pressure gauge 80 for indicating the pressure in vessel 12 is connected by pipe 81 through a pressure switch 82 which in turn is connected to pipe 83 communicating rwith the interior of vessel 12 through an upper portion thereof. Pressure switch 82 is arranged to relay signals for closing regulating valves 77 when the pressure in vessel 12 reaches about 15 p.s.i.g. and for opening valve 77 when the pressure in vessel 12 is decreased to about 10 p.s.i.g. Thus, the burners 75 will be on while the pressure in Vessel 12 is building up to 15 p.s.i.g. and olf both when the pressure reaches about p.s.i.g. and during the relieving of t-he pressure to about l0 p.s.i.g. The burners 75 ycorne on again at l0 p.s.i.g. Pressure switch 82 also is arranged to provide electrical signals to solenoid valve 68 for opening and closing same at about l5 p.s.i.g. and about 10 p.s.i.g. respectively. Thus, steam, some impurities, and fat containing a high incidence of free fatty acids will fbe relieved from vesselV 12 through pipes 66 and 71 when the pressure in vessel 12 builds up to about 15 p.s.i.g. and will continue to be relieved -until the pressure in vessel 12 decreases to about l0 p.s.i.g.

A thermocouple 90 of any well known type is suitably supported by vessel 12 and is positioned for immersion in the fat 13. Thermocouple 90 is electrically connected with regulating valve 77 through a suitable controller, not shown, for regulating the flow of gas to the burner 75 and to thereby control the temperature of fat 13 in vessel 12.

The operation of the apparatus and method of the present invention is preferably performed automatically. The control circuitry shown schematically in FIG. 2 is representative of a circuit which can be used for automatic operation of the present invention. A typical cooking cycle of chicken sections will best illustrate one operation of the cooking system of the present invention. The chicken to be prepared is suitably breaded and placed on the mesh trays 14 which in turn are put on support rod 15. The fat in container 21 is heated to a desired temperature by turning on the electric power to heater 27. The fat in container 21 is raised to a temperature suicient to drive olf moisture to thereby prevent oxidation of the fat. A suitable temperature would be about 250 F. If the fat were already at or above 250 F. no additional heating would be needed. Assuming then that the temperature of the fat is heated to 250 F. and when this temperature of fat is reached, the main power switch is turned on to connect the control circuitry to the electrical supply buses L1 and L2. At this juncture, it should be noted that in this illustrative description container 23 contains fat which was used in a completed cooking cycle and was directed into container 23 in a manner to be described hereinafter. Pump 29 is activated for pumping fat from containerv 21 to vessel 12 by closing switch 102 which energizes timer 104 thus closing holding switch 105 thereby causing switch 106 to close, to thereby energize motor 30 which then drives pump 29. Timer 104 is a cam type program timer set for the total pumping time necessary to pump the fat from container 21 to vessel 12. The amount of fat to be pumped into vessel 12 is determined by the amount necessary for cooking the maximum capacity of chicken in the Vessel 12. For example, approximately 175 pounds of fat heated to about 425 F. would be needed here to cook between 60-80 pounds of chicken sections in about eleven minutes. It should be made clear, however, that this same 175 pounds of fat heated at a temperature below 425 F. can be used to cook lesser amounts of chicken by virtue of the present invention. Returning to the operation of the invention, the contacts of switch 106 remain closed and thereby energize the coils 108 and 110 of valves 26 and 40, respectively. A control relay 117 is also energized -which in turn caused contacts 109, 113, 114 and 115 to close to energize pump motor 30 to thereby rotate pump -29 for lling vessel 12 with fat. Afer a preselected period of time, contacts in timer 104 open to thus deenergize coils 108 and 117 whose contacts 109 open to deenergize coil 110, thus opening contacts 113, 114, and 115 to thereby stop pump motor 30 at which time the vessel 12 is -lled with the desired amount of fat 13. A short time (viz 15 seconds) after the cam contacts 106 in timer 104 open, cam contacts 116 also in cam program timer 104 close to energize selenoid 118 to open main valve 77 in gas line 76 for permitting gas flow to burners 75. Main valve 77 is controlled for on-otf operation by temperature controller 120 set at cooking temperature, to be elaborated upon later, and is supervised by pressure limit switch 124 and high temperature limit switch 122 suitably connected to thermocouple 90. A ame failure burner protection is provided by a well known type of thermoelectric thermocouple and valve, not shown. A suitably colored light 211 indicates that burners 75 are on. A short time (viz l5 seconds) after the contacts 116 of timer 104 close, cam contacts 125-also in cam program timer 104 close to energize the coils 127 of solenoid valve 57 and control relay 129 whose contacts 111 and 119 close to energize coil 108 of solenoid valve 26 with powering relay 117. Control relay 129V is also energized to close contacts 130, 131, and 132 to reverse the direction of rotation of motor 30 and accordingly, pump 29 to thus pump fat from container 23 to container 21. During the transfer of fat between containers 23 and 21, the fat is ltered of virtually all particulate matter by passing through filter 53. After a predetermined period of time after the closing of the contacts 125 of timer 104 contacts 140 ot timer 104 open to deenergize coils 127 of valve 57 and relay 129 to deenergize coil 108 21 and vessel 12 now hold fat while container 23 is empty.

This sequence of filling vessel 12 with heated fat from container 21 and filling container 21 with filtered fat from container 23 is illustrated diagrammatically in FIGS. 3 and 4.

Continuing with the operation of the invention, a temperature switch 150 closes at a preset temperature setting (cooking temperature) at which time signal light 151, comes on and this indicates that the vessel 12 can now be loaded with chicken. The tray 14 supported chicken is then placed in vessel 12 so that all the chicken is irnmersed in the rfat 13. The cover 16 s then clamped shut to thereby seal the vessel 12. The time for cooking a food productafter vessel 12 is sealed is dependent on the Aamount of food to be preparedmore food requires more time--as well as the nature of the food (viz chickenV l of food to be prepared. The cooking temperature, set before sealing vessel 12, would be about 425 F. for example, with 60-80 pounds of chicken to be cooked. More or less chicken would require the fat temperature'toY be accordingly increased or decreased. It is preferable, however, `not to raise the temperature of the fat above 500 F. Likewise, the total cooking time will vary with the amount of product, nature of product, and the like. With the vessel 12 sealed, the internal pressure will build up due to the generation of steam from the chicken. The ternperature of the fat 4will also decrease. When the internal pressure reaches about l p.s.i.g. the contacts of pressure switch 160, forming part of pressure switch 82,close and power control relay 162 which in turn energizes cooking timer 164 through contacts 165. Holding switch 167`is closed to maintain power to cooking timer 164. Art this juncture of operation, the actual pressure cooking begins."

The pressure switch 160 energizes coil 170 of: solenoid valve 68 to thereby open valve 68 to release tov sewer a certain amount ofv steam and impurities, including free fatty acids, driven -from the chicken to thereby decrease the internal pressure of vessel 12. At the same time as coil 170 is energized, `contacts 172 open to deenergize coil 118 of main gas valve 77 to thereby close off the gas supply to burners 75 to cease heating of fat 13. The pressure continues to decreaseto about p.s.i.g. at which point pressure switch 160 deenergizes coil 170 to close valve 68. At the same time as coil 170 is deenergized contacts 172 close to energize coil 118 of rnain gas valve 77 to open the gas supply to burners 75 and resume heating of fat 13. This cycle repeats itself throughout the cooking of the chicken. The venting of the steam betweenlS p.s.i.g.V

and 10 p.s.i.g. results in an elimination of some impurities urged out of the chicken during cooking vandsome Vfree fatty acids formed during cooking. The fat after used for cooking and after being returned to container., 21, is the same to the naked senses of sight, taste, smell, and,k touch as it was before a cooking cycle. Furthermorethe venting of steam reduces the amount of water whichl can remain in the fat 13, thereby reducing the detrimental effect of hydrolyzing the fat to form free 'fatty acids. It was noted hereinbefore in the introductory portion of this detacts 190 close energizing relay 191 opening contacts 192 to assure turn o' of y'burners 75. As noted earlier in the -description of the operation, the cooking time is dependent on the nature and amount of food to be prepared and on -thetemperature of the cooking fat. For example, the timer 164 would be set for eleven minutes for between 60 and 80 pounds of chicken to be cooked at 425 F. initial fat temperature. Less chicken would require a shortened cooking time, as well as a lower cooking temperature. Contacts 190 also energizes time delay relay 193 which energizes coil 194 of solenoid valve 45 through contacts 195. The fat is now discharged from vessel 12 under the urging of the internal steam pressure. As the fat 13 passes from vessel 12 to container 23, steam contacts the chicken to drive excessive Vfat therefrom as well as returning a certain amount of moisture into the chicken. After timer delayfrelay 193 times out, contacts 197 close to energize coil 199-of solenoid valve 87 to open valve 87 and vent the excess steam from vessel 12 to sewer. At the same time contacts 195 open to deenergize coil 194 of solenoid valve to thereby close valve 45, Thus, as soon as all of the fat is out of vessel 12 the remaining steam is vented to sewer. The discharge of fat 13 from vessel 12 to container 23, and the venting `of steam to sewer after discharge of fat, is diagrammaticallyfillustrated in FIGS. 5 and 6. The chicken is now ready to be removed from vessel 12. The cover 16 is unlatched, the trays of chicken removed, and the chicken distributed for consumption as V207 and 208 to start pump motor 30, and accordingly,

pump 29. Thus, as illustrated in FIG. 7, the fat 13 is pumped 'into container 23.' As well as being useful as an emergency discharge means for the fat in the vessel 12, this pumping can be used for removing fat from vessel 12 when cooking certain foods in an open vessel such as potatoes and certain sea foods, for example. A manual selector switch 210 is shown for purposesv of providing manual operation of burners 75 by supplying power to energize coil Y118 of gas valve 77. The steam 'in vessel 12 can be manually relieved by actuating switch 220 to supply power to energize coil 170 of solenoid valve 68. Finally, a switch 230 is'providedfor manual opening and closing of solenoid Valve 45 to give'a pulsing type of fat discharge from vessel v12. Many variations can be incorpo Y Those 'skilled inY the art could readily attest to this. However, it" should be* clearlyiunderstood that the circuitry shown and described herein is only typical and should not lbe considered-fas `the onlyfcircuitry available for the present' invention.

'fThecooked'chicken' emergeswith a crisp coating hav- VMing browned, appetizing appearing color. It is uniformly thoroughly cooked to thebone and is moist vand tasty.

Furthermore, all the'chicken is uniformly cooked-between the bottom-most tray 14 to the top-most tray 14. This extraordinarily cooked product is attributable to regulating the heatingofthe fat 13 between pressure relieving and the steam content in vessel 12 during the cooking of the chicken-This heat and steam regulation was elaborated upon .hereinbefore in the introductory portion of this description. All of the fat is virtually removed from each piece of chicken, Chicken cooked by the present invention can b e placed on absorbing paper. and lremoved without leaving a heavy grease spot of the nature which would be I leftuby chicken" deep fried by thec'ornrnonly used deepfry Y systems. There will be some fat remaining in the chicken p prepared by the present invention but lthe amount of the remaining fat will be vvery small and just enough to add flavor tothe finished chicken. v

It has been found that cooking fat used with the present invention can be reused for an indefinite period at a great cost savings. No unusual change in the fat can be discerned over a prolonged period of use of the original fat. This long fat life is attributable to the removal of some impurities, free fatty acids, and steam from the cooking vessel during cooking and thereby eliminating the major causes of fat breakdown. Furthermore, high temperature (viz 425 F.) fat can be repeatedly used over long periods of time without danger of subjecting the fat to rapid breakdown. Thus, the food product can be cooked quickly with low fat absorption. It should be carefully noted that the heavier particulate impurities are removed by the filters and not dun'ng the pressure relieving. The many other advantages of the present invention have been set out in the earlier portions of this description.

The relieving of the pressure during cooking, as described above, is important for obtaining a well cooked and clean product, as well as for providing a continuing removing of some impurities including free fatty acids from the cooking vessel and regulating the steam content in the vessel during the cooking period. Although the pressure relieving was described between about 15 p.s.i.g. and l p.s.i.g. it is emphasized that other different ranges of pressure relieving can be applied to suit a d esired need.

It must be clearly understood that the present invention can be used in cooking any kind of` food which can be pressure cooked. The present invention is not to be construed as limited to the cooking of chicken, nor to the quantity of product illustrated, since the present system can be readily adapted to cook very large quantities of food (viz 200G-5000 pounds). The preparing of deep fried chicken was described purely as an illustration of a typical product capable of being prepared by the present invention` By modifying the system previously described and shown in FIGS. l-7, I can put water in the cooking vessel 12 and cook food products such as fish, stewed chicken, beans, rice, noodles, peas, pot roasted beef, potatoes, and many others, too numerous to list. In all cases the cooking cycle is essentially the same, in that the product is immersed in a hot liquid cooking medium, the pressure in the sealed vessel is relieved between two predetermined pressures, the heat preferably turned olf during relief and on when relief is stopped and the cooking medium is then discharged at the end of the cooking period. For example, salmon, tuna, and Swordfish were immersed at different times into water and cooked while relieving the pressure within the vessel between 30 and 26 p.s.i. The fish was cooked for about thirty minutes, timed from the first pressure relief. The fish samples were tested for mercury before and after they were cooked. Certain test results showed that the mercury content in the fish decreased as a result of being cooked following my method.

It is to be noted that when I use the word immerse I mean placing the food either wholly or partially into the cooking medium. In one cooking of navy beans, twenty-five pounds of dry beans were immersed in eleven gallons of boiling water. The beans were cooked for about five minutes and during the pressure relieving the steam was trapped, condensed and collected. The beans were thoroughly cooked and -very clean. The collected steam, condensed to water, contained a high incidence of dirt clearly visible to the naked eye.

As well as making the system of my present invention capable of using water or the like, as the cooking medium, further modification can be made wherein my system can selectively use either water or fat as the cooking medium. Such a system is schematically illustrated in FIG. 8, and includes a high pressure cooking vessel 112 adapted to be closed in a pressure-tight condition by cover 116. Vessel 112 communicates through suitable plumbing with a pair of storage containers 121 and 123. Container 121 is used for storing clean fat while container 123 receives and temporarily stores fat used in a previous cooking cycle. Container 123 also houses suitable filter elements, not shown, which serve to remove a large portion of solid particulate matter entrained in the fat during the cooking cycle. A suitable gas heater 126 is arranged externally of container 121 for preheating clean fat prior to passage of such fat to the cooking vessel 112. A line 128 containing a motorized valve 229 communicates between container 121 and vessel 112. Container 121 is arranged with respect to vessel 112 so that clean fat from container 121 can be passed to vessel 112 by gravity. Vessel 112 communicates with container 123 through a line 330 having a motorized valve 232 therein. A line 133 extends from line 330 through a solenoid operated valve 134 to the inlet of a motor driven pump 135. A line 136 branches off from line 133 through a manual operated valve 137 to container 123. Line 138 extends from line 133 through a solenoid operated valve 139 to a drain line 240. Line 142 extends from container 123 through a solenoid operated valve 143 to the inlet of pump 135. The outlet of pump is connected to container 121 by line 145 through a solenoid operated valve 146. The outlet of pump 135 is also connected to container 123 by line 250 branched into line 145 through a solenoid valve 152 and into line 136. Steam is purged to drain 240 from vessel 112 through line 260 having a solenoid valve 262 therein.

The cooking medium in vessel 112 is heated by gas burners connected to a source of gas through line 176. The flow of gas to the burners 175 is regulated by regulating valve 177 suitably connected with line 176.

A pressure gauge 280 for indicating the pressure in vessel 112 is connected .by line 281 which also includes a pressure switch 182 and relief valve 184. Pressure switch 182 is arranged to relay signals for closing regulatin-g valve 177 when the pressure in vessel 112 reaches a predetermined low value.

Line 290 is connected between a source of water, not shown, and vessel 112, and contains a suitable pressure regulator 292, a motorized valve 294, and a hand operated valve 196.

A cooking cycle using either water or shortening can be automatically controlled in the same essential manner as previously described with regard to the embodiment of my system illustrated in FIGS. 1-7. A control circuitry is not described for the system of IFIG. 8, but could be readily ascertained by those skilled in this art.

While I have shown and described certain present preferred embodiments of the invention and have illustrated certain present preferred methods of practicing the same, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

I claim:

1. A method of cooking foodstuffs comprising the steps of: immersing foodstuffs in a scalable pressure vessel containing a liquid cooking medium; closing the vessel to render it pressure-tight; heating the cooking medium until the pressure in the vessel increases to a predetermined high pressure value as the moisture and impurities in the foodstuffs are vaporized; relieving the pressure in the vessel from said high pressure to a predetermined low pressure value, thereby releasing a portion of entrapped steam; and repeating said heating and said relieving until the foodstuffs are cooked.

2. The method as set forth in claim 1 wherein said immersing of foodstuffs is in a preheated non-aqueous liquid cooking medium at a temperature of between 350 F. and 500 F.

3. The method as set forth in claim 1 wherein said heating is discontinued during said relieving step.

4. The method as set forth in claim 12 wherein said discharging is from a position in the vessel such that the steam therein, -while urging the cooking medium outwardly of the vessel, contacts the foodstuffs.

1'1 5. The method as set forth in claim lz-wherein-V said ventingis commenced substantially simultaneously upon completion of said discharging of the. cooking medium. v 6. The method-as set forthl Vin claiml 12 includingthe additional step of filtering the. discharged cooking medi- Y um of substantially all solid impurities therein whereby the discharged cooking medium is then substantially impurity free and ready for reuse. l j

7. The-methodA as set forth in claim 1 wherein said heating ismaintained until the pressure vin the vessel -increases to. about 15 p.s,i.g.v ,I t. j

8. The method asset. forth in claim 3 wherein said heating is resumed whenthe pressure in the vessel -isdecreased to about 10 p.s.i.g.

9. A method of preparing foodstuffs for human-consumption comprising Vthe steps of: preheating` a mass of -liquid cooking medium in a scalable pressurevessel to a temperature to between about 3505v F. and-500 F.;;im mersing the foodstuffs into the preheated cooking ..medi um; closing Ithe vessel to render it pressure-tight; heating the cooking liquid until the pressure in the vessel increases to about 15 p.s.i.g.; relieving the .pressure in the vessel while-at the same time discontinuing said heating from about 15 p.s.i.g. to about 10 p.s.i.g. thereby releasing a portion of entrapped steamgenerated from thethe vessel, contacts. the foodstuffs; venting the vessel of all of the steam-therein upon completion of the discharging of the cookingliquidfiltering the discharged cooking liquid of, substantially allof the solid impurities therein wherebythe cookingliquidis substantially impurity free and ready for-:reuse` 1Q.- A;method. of preparing foodstuffs as set forth in claimA 9,- whereinfsaid Nenting is commenced substantially simultaneously uponcompletion of the discharging -of thelcookingliqnidg 1L A' methodgofpreparing foodstuffs asset forth in claimv9 where-inf; said venting occurs at a lower portion of the' vessel-'and;;below the foodstuffs being prepared; and said-venting.. occurs substantially simultaneously upon completion of the dischargingV of the cooking liquid.

12. The'rnethod as set forth in claim 1 including the 'additional -steps lof discharging the cooking medium from the vesselunder the-urging of the pressure of the steam the vessel after the foodstuffs are substantially cooked,

and venting the vessel of all of the steam therein upon completionzof said-discharging of the cooking medium.

-i -References Cited UNITED STATES PATENTS 2,359,932 i2/i945 Auen 99-33ox 3,431,835 3/1969 Angola 99-408 `3,466,997 v 9/13'69v Hartzog 99-330 HYMAN LORD, Primary Examiner Us. c1. x.R. 42e-509 f 

